The basic problem is one of intimately processing, for example, mixing a plurality of fluids, i.e.: intimately mixing a gas in a liquid or a liquid in another liquid, or more than two phases, with accurate control of the passage of the two (or more) phases through the active portion of the device in which such mixing takes place. Secondarily and specifically, the problem is to prepare emulsions for chemical and pharmaceutical applications, to gasify liquids for purification and for chemical reactions, to accelerate physical and chemical reactions, and to suspend fine particles. Another problem is to intimately mix two reactive materials instantaneously as they enter a sonication or cavitation field. In many of the foregoing, it is also critical to control the atmosphere in which these processes take place, or to exclude any atmosphere. Fluids to which reference is made herein may or may not include entrained solid particles.
Prior art references describe four application methodologies. The first methodology (1) was the placement of the fluids in the tank of an ultrasonic cleaning bath or similar cavitating open vessel, as described quite extensively in early publications, such as "Ultrasonics . . . Science of a Coming Technology" (unattributed), in Industrial Laboratories, April 1952, and "Ultrasonically Induced Cavitation in Water" by G. W. Willard of the Bell Telephone Laboratories, in the Journal of the Acoustical Society of America, Volume 25, Number 4, Pp. 669-686, July 1953, and in U.S. Pat. Nos. 3,351,539 and 4,576,688. A further development of this methodolgy was the closure of the tank or vessel such that liquid could flow in a controlled manner in and out of the energy field, usually accompanied by provision of additional radiating surfaces to increase the intensity of the energy field, as described in Heat Systems-Ultrasonics, Inc. Technical Note HSU-TN-1, "Industrial Scale Ultrasonic Liquid Processing", dated April 1984. A second methodology (2) was the introduction into a static bath, containing two or more fluids, of a probe vibrating at sufficier high amplitude and frequency to generate cavitation, the creation of shock waves in liquid by formation and collapse of vapor bubbles, as described in U.S. patents such as U.S. Pat. No. 3,246,881. A further development of this technique was the enclosure of the probe tip and liquid bath in a pressure vessel with inlet and outlet provisions, thereby allowing pressurization of the bath and continuous flow of the liquid and other fluids, as described in Heat Systems-Ultrasonics, Inc. brochure S-803 dated May 1962 and in U.S. Pat. Nos. 3,394,274; 3,715,104; and 4,244,702. The third methodology (3) was the passage of the fluids past a vibrating knife edge or reed by which means cavitation was induced in the primary liquid, as described in Bulletin 60 from Sonic Engineering Corp. and in literature covering the SONOLATOR device from Sonic Engineering Corporation. The fourth methodology (4) was the forcing of fluids at extremes of pressure through greatly restricted orifices such that very high rates of shear were generated in the primary liquid, resulting in cavitation, as described in literature from APV-Gaulin Corp. One of many methods of purifying water through the introduction of ozone is discussed in U.S. Pat. No. 4,548,716, while one of many methods of purifying liquids and other substances by the application of ultrasonic energy is discussed in U.S. Pat. No. 4,477,357.
Prior art systems and methods are shown and described in Reprint PVI-2 entitled "Application of Ultrasonic Liquid Processors (Power vs. Intensity in Sonication)", by S. Berliner, III, dated April, 1985, available from Heat Systems Incorporated, 1938 New Highway, Farmingdale, N.Y. 11735, which describes typical equipment and applications; in "The Chemical Effects of Ultrasound", Pp. 80-86, SCIENTIFIC AMERICAN, February 1989, by Dr. Kenneth S. Suslick, which describes processes; and in Bulletin S-803, entitled "New Branson SONIFIER", available from Branson Instruments, Inc., which describes a device.
The problems with the prior art, systems and methodologies lie in (1) assuring uniform treatment of all aliquots or fractional parts of the fluid media being treated, (2) assuring that the proportions of the phases are accurately maintained during treatment, (3) assuring that equal amounts of all phases are present in the energy field at all times during treatment, (4) avoiding extremes of pressure in order to minimize the great danger presented by such pressure, and (5) controlling or excluding the atmosphere in which treatment occurs. A major drawback in the use of parallel plate transducers, and in cylindrical or polygonal transducers, which radiate inwards toward the longitudinal center of a flow path is that there are "dead" spots, places where vibrations cancel each other.
The system and method of this invention differs from the prior art systems and methods in that this system and method uses concentric delivery passages or tubes through which the fluids are introduced into a high-intensity energy field in which cavitation is induced in the primary liquid. The major advantage offered by this arrangement is that the two (or more) parts of a resin, or similar material, are not brought into contact in any way outside of the sonication field. Injecting one part through, for example, an outer tube while injecting another part through an inner tube brings them into the sonication zone simultaneously. The central origin and radial flow assures uniformity of treatment of all aliquots, unlike the situation which pertains with the current devices.
As described in greater detail in the references by Berliner and by Suslick hereinbefore cited, the action of ultrasound in a liquid at extreme intensity results in the repeated rapid formation and extremely violent collapse of bubbles, generating shock waves which radiate throughout the liquid, a process known as cavitation or sonication. The collapse of the bubbles and passage of shock waves through a liquid containing other liquids, immiscible in the parent liquid, or gases or fine solid particles results in mixing, emulsification, gasification, deagglomeration and disaggregation, suspension and dispersion, and even the creation of new compounds otherwise unobtainable. This comes about from the high pressure and temperature generated in the collapse and in the passage of the shock wave and related effects, in which theoretical values of 10,000 atmospheres and 20,000.degree. K. might obtain and in which actual values of at least 500 atmospheres and 5,500.degree. C. have been calculated (Suslick, op. cit.). Such intense energy levels provide the means whereby the processes described can be enhanced and accelerated. Precise control of the introduction into, and passage through, the cavitation or sonication field or zone of the materials to be processed is all the more critical as the intensity increases. The present invention provides a superior means of achieving optimum results in a manner not hitherto practiced.